<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <button>按钮1</button>
  <button>按钮2</button>
  <button>按钮3</button>
  <button>按钮4</button>
  <button>按钮5</button>
</body>

</html>
<script>
  //获取所有元素
  var btns = document.getElementsByName('button')
  //为所有按钮元素注册相同事件处理函数
  for (var i = 0; i < btns.length; i++) {
    btns[i].onclick = changeColor;
  }

  function changeColor() {
    for (var j = 0; j < btns.length; j++) {
      if (btns[j] === this) {
        //设置当前按钮的背景颜色
        this.style.backgrounderColor = '';
      }
    }
  }
</script>